package com.hmdp.utils;

import cn.hutool.core.util.BooleanUtil;
import cn.hutool.core.util.StrUtil;
import cn.hutool.json.JSONObject;
import cn.hutool.json.JSONUtil;
import com.hmdp.entity.Shop;
import lombok.extern.slf4j.Slf4j;
import org.springframework.data.redis.core.StringRedisTemplate;
import org.springframework.stereotype.Component;

import javax.annotation.Resource;
import java.time.LocalDateTime;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;
import java.util.concurrent.TimeUnit;
import java.util.function.Function;

import static com.hmdp.utils.RedisConstants.*;

/**
 * @BelongsProject: hm-dianping
 * @BelongsPackage: com.hmdp.utils
 * @Author: 成希
 * @CreateTime: 2025-05-25  10:58
 * @Description: TODO
 * @Version: 1.0
 */
@Component
@Slf4j
public class CacheClient {
    @Resource
    private StringRedisTemplate stringRedisTemplate;

    public void set(String key, Object value, Long time, TimeUnit unit){
        stringRedisTemplate.opsForValue().set(key,JSONUtil.toJsonStr(value),time,unit);
    }
    public void setWithLogicExpire(String key, Object value, Long time, TimeUnit unit){
        //设置逻辑过期
        RedisData redisData = new RedisData();
        redisData.setData(value);
        redisData.setExpireTime(LocalDateTime.now().plusSeconds(unit.toSeconds(time)));
        //写入redis
        stringRedisTemplate.opsForValue().set(key,JSONUtil.toJsonStr(redisData));
    }
    //缓存穿透
    public <R,T> R queryWithPassThrough(
            String keyPrefix, T id, Class<R> type, Function<T,R> dbFallback,Long time, TimeUnit unit){
        String key=keyPrefix+id;
        //1.从redis查缓存
        String json = stringRedisTemplate.opsForValue().get(key);
        //2.判断是否存在
        if (StrUtil.isNotBlank(json)) {
            //3.存在 返回

            return JSONUtil.toBean(json, type);
        }
        //判断命中的是否是空值 如果是空值
        if (json!=null)
        {
            //返回一个错误信息
            return null;

        }

        //4.不存在 根据id查询数据库
        R r =dbFallback.apply(id);
        //5.不存在 返回错误
        if (r == null) {
            //将空值写入redis
            stringRedisTemplate.opsForValue().set(key,"",CACHE_NULL_TTL,TimeUnit.MINUTES);
            return null;
        }
        //5.存在 写入redis
       this.set(key,r,time,unit);

        return r;
    }
    private  boolean tryLock(String key){
        Boolean flag = stringRedisTemplate.opsForValue().setIfAbsent(key, "1", RedisConstants.LOCK_SHOP_TTL, TimeUnit.MINUTES);
        return BooleanUtil.isTrue(flag);
    }
    private void unlock(String key){
        stringRedisTemplate.delete(key);
    }
    private static final ExecutorService CACHE_REBUILD_EXECUTOR = Executors.newFixedThreadPool(10);
    public <R,T> R queryWithLogicalExpire(String keyPrefix, T id ,Class<R> type,Function<T,R> dbFallback,Long time, TimeUnit unit) {
        String key = keyPrefix + id;
        // 1.从redis查询商铺缓存
        String json = stringRedisTemplate.opsForValue().get(key);
        // 2.判断是否存在
        if (StrUtil.isBlank(json)) {
            return null;
        }
        // 4.命中，需要先把json反序列化为对象
        RedisData redisData = JSONUtil.toBean(json, RedisData.class);
        R r = JSONUtil.toBean((JSONObject) redisData.getData(), type);
        LocalDateTime expireTime = redisData.getExpireTime();
        // 5.判断是否过期
        if(expireTime.isAfter(LocalDateTime.now())) {
            // 5.1.未过期，直接返回店铺信息
            return r;
        }
        // 5.2.已过期，需要缓存重建
        // 6.缓存重建
        // 6.1.获取互斥锁
        String lockKey = LOCK_SHOP_KEY + id;
        boolean isLock = tryLock(lockKey);
        // 6.2.判断是否获取锁成功
        if (isLock){
            CACHE_REBUILD_EXECUTOR.submit( ()->{

                try{
                    //查询数据库
                    R r1 = dbFallback.apply(id);
                    //写入redis
                    //重建缓存
                    this.setWithLogicExpire(key,r1,time,unit);
                }catch (Exception e){
                    throw new RuntimeException(e);
                }finally {
                    unlock(lockKey);
                }
            });
        }
        // 6.4.返回过期的商铺信息
        return r;
    }
}